Mobile communication systems typically operate in environments that contain many sources of interference signals. These interference signals are often dynamic, asynchronous, and vary in intensity. The interference signals may have different frequencies—for example, some interference signals may be 12.5 kHz above the frequency band within which the system operates, while other interference signals may be 25 kHz above the frequency band of interest, and yet other interference signals may be approximately 1 MHz above the frequency band of interest.
Receivers in mobile communication systems contain phase locked loops (PLLs) that produce noise. This noise frequently combines with the aforementioned interference signals to corrupt the signals in the frequency band of interest. This corruption may be mitigated by minimizing the noise produced by the PLLs. Controlling PLL noise, however, is a power-intensive endeavor.